In conventional paper web perforating systems, and in conventional procedures for producing perforated business forms or the like from paper webs, when two sets of perforations are desired the web is passed over an anvil cylinder and perforating blades (or like perforating elements) on each of a pair of perforating cylinders which are rotated into contact with the web as it passes over the single anvil cylinder. When it is desired to adjust the spacing between the first and second sets of perforations formed by the perforating cylinders, it is necessary to adjust the position of one of the perforating cylinders with respect to the other perforating cylinder and the anvil cylinder. Such an adjustment is difficult and often imprecise. Utilizing such a conventional system and procedures, when the perforating blades must be periodically changed, two sets of blades (one associated with each set of perforating cylinders) must be replaced, resulting in a significant amount of down time at that particular point in time. Further, if it is desirable to use the system to form only a single set of perforations, one of the perforating cylinders must be moved out of operative association with the anvil cylinder.
According to the present invention an assembly and method are provided which overcome the drawbacks of the prior art system and procedures set forth above. In particular, according to the present invention a single perforating cylinder is utilized, and it is disposed in operative association with first and second anvil cylinders. All of the cylinders are rotatable about parallel, spaced axes, and the first and second anvil cylinders are mounted with respect to the perforating cylinder so that the web perforating elements (e.g. interrupted blades) extending outwardly from the perforating cylinder cooperate with the anvil cylinders so that a paper web passing between the perforating cylinder and one or both of the anvil cylinders is perforated thereby.
In the preferred embodiment of the assembly according to the invention, the spacing between the first and second sets of perforations formed in the web by cooperation between the perforating cylinder and the first and second anvil cylinders, respectively, is precisely controlled by adjusting the length of the web between the first, and second anvil cylinders. Preferably a compensator roller is provided over which the web passes, and the spacing of the compensator roller with respect to the perforating cylinder is adjusted by moving the axis of rotation of the compensator roller with respect to the perforating cylinder.
In addition to the compensator roller, various additional rollers are provided for directing the web in its path between the first and second anvil cylinders. Additionally, another roller, or other rollers, are provided so that the web may move in an alternate path in which after it passes between the first anvil cylinder and the perforating cylinder it bypasses the second anvil cylinder, so that only a single set of perforations is formed in the web. In all cases, the axes of the perforating cylinder and the first and second anvil cylinders remain stationary with respect to each other, and only the lighter, more easily controlled, compensator roller need be moved.
The invention also relates to a method of perforating a paper web in the production of business forms and the like utilizing a single perforating cylinder and first and second anvil cylinders, including precisely controlling the spacing of the sets of perforations formed in the web by cooperation between the perforating cylinder and the first anvil cylinder, on the one hand, and the perforating cylinder and the second anvil cylinder, on the other.
It is the primary object of the present invention to provide an apparatus and method for the simple, effective, and versatile perforation of a web, such as a paper web in the production of business forms. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.